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Aug. 11, 1959 K. B. BREDTSCHNEIDER ET AL 2,899,667

CONNECTOR FOR THE CONSUMABLE ELECTRODE OF AN ARC MELTING FURNACE Filed Feb. 21, 1955 6 Sheets-Sheet 1 E5 a E \E l jl II E I v E 1 I n i. I I 36 29 r P 13 a, Z9

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CONNECTOR FOR THE CONSUMABLE ELECTRODE OF AN ARC MELTING FURNACE Filed Feb. 21, 1955 6 Sheets-Sheet 3 K. B. BREDTSCHNEIDER ET AL 2,899,667 CONSUMABLE ELECTRODE OF AN ARC MELTING FURNACE Aug. 11, 1959 CONNECTOR FOR THE e SheetsSheet 4 Filed Feb. 21, 1955 J75 J67 J76 &

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Aug- 11, 1959 K. B. BREDTSCHNEIDER ET AL 2,899,667

CONNECTOR FOR THE CONSUMABLE ELECTRODE OF AN ARC MELTING FURNACE Filed Feb. 21, 1955 I 6 Sheets-Sheet 6 mezz ons Jredfisvixg/aer;

United States Patent Ofiice Patented Aug. 11, 1959 CONNECTOR FOR THE CGNSUMABLE'. ELEC- TRODE OF AN AR MELTING FURNACE Kurt B. Bredtschueider and-Frank M. Onak, Chicago, 111-, and Murray H. Stuart, New York, N.Y., assignors to Crane Co., Chicago, 111., a corporation of Illinois Application February 21, 1955, 'Serial No. 489,517 1 Claims. (Cl. 3399) 1 The present inventionrelates to an electric arc type of melting furnace, and more particularly, it pertains to a furnace and electrode feed assembly particularly adapted to melt consumable electrodes of refractory metals, such as titanium and zirconium,-for example.

It should be noted at the: outset that many difficulties confront producers of titanium metal which are not usually encountered in ordinary metalfurnace operations. These difficulties are essentially the results of the high melting point of titanium metal, to wit, 1800 degrees centigrade, and of the need for maintaining a continuous inert atmosphere in the course of all furnace operations. The

latter need is a necessary precaution occasioned by the gathering ability or the great affinity of titanium for gases of the atmosphere. Unless a proper furnace temperature and suitable inert atmosphere are continually present, nonuniform ingots of contaminated metal will result which are worthless for the usual commercial applications of titanium.

It is partially in solution of the above two problems that some of the novel aspects of our invention are concerned.

in addition, it is one of the objects of our invention'to presenta contact for transmitting-the arcing current to a consumable electrode member. The contact member is fluid activated and cooled and possessesa desirable safety feature as will hereinafter be explained in greater. detail.

Another object of our invention is to provide an electrode guide casing which is relatively easily dismantled and rendered readily disengageable from a fixed electrode housing member, whereby new consumable electrodes may be conveniently loaded with little or nodanger of electrode fracture or damage occurring.

It is a further object of our invention to provide a type of gas-tight seal employing double concentric O-rings with an inert gas pressure maintained in the annular path defined thereby.

It is a further object ofour invention to provide a type of gas-tight seal employing double concentric O-rings with an inert gas pressure maintained in the annular path defined thereby.

It is astill further object of our invention to provide a furnace design in which a protective inert gas overpressure is maintained in the vertically aligned chambers positioned above the arcing chamber thereby preventing the entrance into the upper chambers of undesirable metallic vapors which rise from the melt surface.

These and other objects and advantages of our invention will become more apparent upon proceeding with the following detailed description read in the light of the accompanying drawings, in which Fig. l is a sectional view of our invention showing the arcing crucible.

Fig.- 2 is" a sectional View of the electrode contact chamber.

Fig. 3 is' asectional view taken on-line 3-3 of Fig. '2.

Fig.4 is a sectional viewofa modified form of electrode feed taken on the line 4-4 of Fig.- 5.

Fig. 5 is an end exterior view of the said modified form of electrode feed referred to in Fig. 4.

Fig. 6 is a transverse sectional view of electrode feed taken on the line 66 of Fig. 7.

Fig. 7 is an exterior view of the modified electrode feed referred to in Fig. 6.

Fig. 8 is a fragmentary view of a preferred form of electrode feed mechanism.

Fig. 9 is a sectional view of the mechanism referred to in Fig. 8 and taken on the line 88 thereof.

Similar reference numerals refer to similar parts throughout the several views.

Referring now more patricularly to Fig. 1, the arc melting chamber 1 is illustrated comprising the copper shell or crucible 2 which is brazed or otherwise suitably joined at its lower end limit in fluid-tight engagement to the shouldered reinforcing ring 9. The titanium button 4 is threadedly engaged or otherwise aflixed to the top surface of the crucible bottom 3. Cooling fluid enters the bottom sub-chamber 3 at inlet 5 and exits at discharge outlet 6, as indicated by arrows. it is, of course, obvious that the bottom of the crucible 3 must be adequately cooled at theinitiation of the arcing between the button 4 and the tip of consumable electrode 7, the latter member being indicated in dotted lines;

A substantial reinforcing member, such as a stainless steel outer shell 8 is positioned over the reinforcing ring 9 and is aflixed in fluid-tight manner to the annular-flange member 11 by means of the weld 12. Gasket member 13 maintains a fluid-tight seal between the annular shoulder 15 of the flange member 11 and the overlapping annular shoulder E4 of the reinforcing ring 9. Ring member 16, as indicated, threadedlyengages the reinforcing ring 9 and is suitably tapped at 17 for threadedly engaging annularly spaced apart bolts 13 which maintain the crucible chamher bottom portion 3 and the bottom surface of the reinforcing ring? in fluid sealing engagement by means of the interposed O-rings 19,- while concomitantly forcing opposing flanges Hand 15 together to compress the gasket 13. The outer shell flange member 11 is connected with the water inlet pipe 21 which thus fills the annular cooling chamber 22' asdefinedby-the inner copper shell 2 and the outer steel shell 8.

The ring .member 16 =isalso provided with the square head set-screws ltl threadedly attached thereto to bear against an end surface of the annular flange member 11, and'while on preferably the same bolt circle as the bolts 18 fit'in between th'e latter membersthereby to effect the desired compression on the gasket 13 shouldered on an inner transverse surface of the flange 11.

if desired, andprefer'ably prior to assembly, a high frequency alternating current induction coil 23 may be placed over the-stainless steel shell 8. The purpose of the coil is to-create a magnetic field which stabilizes the furnace arc and prevents objectionable jumping of the arc to the copper shell 2 and thereby avoid a possible burn through. A magnetic field would also create the turbulentaction found in induction furnaces and would be particularly desirable in assuring intimate mixture of any added alloying ingredients with the furnace melt.

It will be noted that the upper'end limit of the copper shell 2 is brazed or otherwise suitably connected to the annular flange member 24 which in turn has a depending annular ring portion 25 preferably formed integral therewith. The ring portion 25 threadedly is connected to the cooling fluid outlet 26 and is maintained in fluid sealing engagement with the upper portion of the outer stainless steel shell'8by means of the interposed O-ring 27.

The entire lower melting chamber assembly is sus pended fromthe floor plate 28 by means of the bolt members 29. The insulating ring members 31 and'32' insure electrical insulation between the consumable electrode 7 and the melt. The electrical lead 30, preferably positive, energizes the melt. It will be noted that the floor plate 28 is cham fered at 33 thereby enabling any vapor condensate accumulated thereon to flow by gravity into the annular channel 34 and thence into the ports 35 of the insulating ring 32 and back into the arc melting chamber generally designated 1.

Particular attention is directed to thenovel double ring construction in combination with gas inlet 37 interposed between the upper surface of shell flange member 24 and the bottom surface of insulating ring member 32 and at other flange interfaces. A positive inert gas pressure relation maintained between O-rings 36 by means of the inert gas inlet connection 37 assures the prevention of atmospheric contamination of the furnace melt since any incoming atmosphere is forcedback outwardly and the inert gas emerging from the said inlet connection 37 is forced inwardly. It will be observed that the same desirable arrangement is provided on the flanged joints throughout the assembly and accordingly bear the same reference numerals.

It should be apparent from the foregoing description that the construction of the arcing chamber assembly is such that both the inner and outer walls thereof may freely expand with increasing temperatures without incurring the danger of leaks as no strains or stresses can arise therefrom because of the unique design employed. It should be further obvious that the illustrated structure is easily and readily dismantleable for the cleaning out of scale or sedimentary matter deposited by the cooling fluid. It also has the desirable advantage of ease of ac cess and replacement of worn-out or damaged parts.

Referring now more particularly to Fig. 2, the superposed electrode contact chamber generally designated 38 is depicted being defined by the annular wall 39 which is welded as indicated to the flange member 41 at the lower end limit and to flange member 42 at its upper end limit. The flexibly formed water jacket 43 is similarly welded to flange members 41 and 42 so as to form an annular cooling chamber in conjunction with the wall member 39. Cooling fluid enters at the inlet 44 and discharges at outlet 45 in the normal course of its operation.

Stud and nut assemblies 48 maintain floor plate 28 and lower flange member 41 of contact housing chamber 38 in tight abutting relationship.

Particular attention will now be directed to the fluid activated electrode contacts generally designated 49. Although four contacts are illustrated (see Fig. 3), it will, of course, be understood that the number may vary with the size of the electrode and the individual requirements of the user.

The electrode contact assemblies 49 are housed in the cylindrical shell members 51 which are welded to flange members 52. Covers 53 are maintained in tight abutting relationship with flange members 52 by means of the nut and stud assemblies 54. The current entering through the cover members 53 from the lead 55, passes through the conducting core 56, through the copper cables 57 which are suitably affixed to the core 56 at one end limit and then through the cup-shaped conducting member 58 to the titanium contact shoes 59. Retaining ring 61 which threadedly engages the end limit of the cup-shaped conductor member 58 permits of rapid and easy replacement of worn contact shoes. Although illustrated as having plane surfaces for use with the electrode having a square or polygonal configuration, the contact shoes 59 may have a contacting face of any suitable design to conform with the electrode peripheral contact surface. The flat insulating gaskets 50 and the flanged insulating portions shown prevent the loss of the arcing current from the cover members 53 to the shell members 51 and overheating of the upper furnace structure in the event the shoes 59 are withdrawn from the electrode as in the case of a cooling fluid failure.

It will be noted that the expansible bellows 62 are welded to ring member 63 at one end limit and to the cup-shaped conducting member 58 at the opposite end limit. Cooling fluid is enabled to enter the fluid-tight chamber 66 formed by the bellows member 62 through the inlet 64 and emerge through the fluid outlet 65 in the normal course of operation. A common circular coil header 60, as illustrated conveniently, serves as common medium to interconnect the respective inlets 64 and outlets 65 for the respective electrode contacts 49. The cooling fluid acts not only to obviate damage resulting from the excessive heating eifects of the arcing operation, but in addition acts as the fluid for a hydraulic ram action forcing the contact shoes 59 against the consumable electrode 7 to effect the electrical contact therewith as illustrated at the inner limit of the inlet 64. By means of a conventional fluid pressure regulating valve 56 suitably mounted on the fluid outlet 65, the fluid pressure of the contact shoes 59 on the consumable electrode 7 may be readily controlled.

It should also be apparent that in the event of a fluid supply failure the pressure forcing the shoes 59 against the electrode 7 will concomitantly be lost and the expansible bellow members 62 which normally have a tendency to retract will do so in the absence of the bellows extending pressure. Under such circumstances, the expansible bellow members function as a safety device in the event of fluid supply failure since the contact shoes 59 will be withdrawn and the arcing operation will cease immediately.

It will be further noted that the conducting cup members 58 in the course of any reciprocal movement occasioned by a cooling fluid failure or change in electrode cross-sectional configuration slidably cooperate with the inner periphery of the insulating ring members 67. The latter members are bolted to the ring member 68 by means of the tap bolt members 72 and 73. The ring member 63 in each case is attached, as by welding, to the shell cylinder 51.

A heat radiation shield 69 is suspended by threaded rod and nut assemblies 71 which are themselves keyed to the ring members 68 by means of the tap bolts 73. The central aperture 74 of the radiation shield is formed to allow the electrode 7 to descend therethrough with only a minimum of peripheral clearance therebetween. It should be understood that the radiation shield 69 therefore functions as a partition separating the lower melting area from the upper axially aligned chambers and allows for the maintenance of a slight overflow of inert gas entering through the inlet 75 (Fig. 2) above the shield and a steady flow of inert gas through the restricted opening into the lower chamber which is connected to a conventional vacuum pump 76 (Fig. 3). The upper portion of the furnace above the shield 69 is therefore maintained cool and free from objectionable vapor condensate and other impurities escaping from the melt, an obvious advantage gained in the course of furnace operation.

As will be more clearly noted from Fig. 3, sight glass 77 and vacuum pump 76 are disposed apart. A melting chamber inlet (not shown) may be disposed opposite the vacuum pump 76 for purposes of adding any desirable alloying elements to the melt.

In Fig. 11, the consumable electrode 7 is contacted in the usual manner by the shoe member 59 and retained to the cup-shaped or hollow element 58 by means of the threaded retainer ring 61, the shoe 59 being gripped by meansof a flanged portion thereof engaging a similar portion on the member 61 as shown. Attached to the interior of the cup-shaped member 58 are the electrical connections for the source of supply 57 molded in a conventional manner to the interior of the member 58. Around the cup-shaped member 58 and in abutting relation are a pa r of axially aligned insulating flanges 152 and 153 joined by means of annularly disposed spaced apart through-bolts at 154 fitted around the sleeve member 155 prior to assembly over the cup member 58. The insulating flanges 152 and 153 are so formed as to fit relatively snugly within the interior cylindrical chamber of the liner 51, the latter member being connected transversely in the usual way to the respective liners for the electrode chamber designated respectively 39 and 43. The liner 51 mounted thereover is provided with a chamher 156 within which an inlet passage is provided as at 157 by means of the tubing connected to a double or telescopically arranged spirally extending coil 159 substantially filling the chamber 156. It should also be noted that the hollow cup-shaped member 58 at one end portion thereof is provided with a chamber 158 suitably connected as indicated by arrows to the outer portion of the coil and connected to the inner coil portion. It will be observed that this arrangement provides for the outlet or discharge to the inner portion of coil 159 and is connected-to the exterior of the chamber 156 by means of the outlet 161 as indicated by the arrows. At the outer end limit of the chamber 156, the liner 51 is connected to an annular flange 162 and having attached thereto a complementary flange 163 with an interposed insulating ring portion 164. All of the latter assembly of flanges and insulators are connected by means of the bolt assembly 165 and have therebetween in seal proof relation the concentrically disposed O-rings 36 and the connection thereto by means of tubes 37, a desirable provision for avoiding entry of undesirable atmospheric gases. The outer flange 163 has a suitable connection for the electrical power source as indicated at 166.

it will be noted that the shaft 167 of a rod-like material extends for substantially the full length of the chamber 156 and in addition projects through the flange 163 for reasons hereinafter explained in greater detail. At its innermost end portion, the shaft 167 is provided with an annular member 168 fixedly attached to the shaft 167 at its inner portion and on its outer periphery to the cup-like member 58. In addition, the ring 168- is apertured to receive the respective inner and outer coils of the coil assembly 159. The shaft 167 is relatively snugly journalled within the sleeve member 171 and suitably connected by means of a weld, as indicated, to the inner surface of the flange 168. A split collar 169 is fitted, as more clearly shown in Fig. 4, around the sleeve 171 and is held snugly thereon by means of the bolt 172 to maintain the electrical contact for the connection 57.

Around the shaft 167 and outside of the flange 163, a suitable stufling box 173 is provided having the stuffing-box bolts 174 and provided with the gland flange 175 held in the customary manner against the flange 176. Within the stufling box 173, the usual packing 177 is applied and held in compression by means of the gland 176. On an outer transverse surface portion of the gland flange 175, the coil spring 182 is suitably mounted having at its opposite or outer end portion a spring cap 179 held in place by means of the threads 178 on the shaft 167. It is maintained in predetermined compressed position by means of the nut 181.

In the aforementioned construction, it will be clear that the inlet 157 is connected to a cooling source directly to the spiral coil 159. This is not only for the circulation of a cooling medium within the liner 51, but also to permit of the desired pressure being exerted within the chamber 158 thereby to establish a desired pressure contact between the shoe 59 and the consumable electrode 7. It will of course be understood in the latter connection that at the outlet 161 a suitable fluid throttling valve may be installed to regulate the amount of fluid discharging from the outlet at 161 and thereby build up sufficient back pressure within the end chamber 158 to create the desired pressure contact against the electrode 7. It will also be 6 understood that the insulating flanges 152, 153 and the insulating ring portion 164 are of a resilient material, thus simulating to some degree the expansibility of a bellows, such the member 62 of Fig. 2.

It will be appreciated also that the method of making these contacts to apply the pressure load against the electrode may take other forms. Some of these are described in the remaining figures and hereinafter referred to in greater detail.

Directing attention now to Figs. 6 and 7, at the outset it will be appreciated that suitable electrical connection with the annular flange 196 is made at 201 simply by means of the bolts 197 also functioning to retain the flange head to the outer flange 187. Electrical current travels through the cap across to the integral connection as at 202 which is preferably made coiled as at 203 thereby to allow for a substantial degree of movement of the cylinder head 133 being attached to the interiorly positioned boss 264 by means of a weld 205 and the bolt 206. In this construction, it should be noted thatin addition to providing a means for cooling the inner portion of the shoe and retainer and 61 respectively of the piston 183 a hollow tube member 207, centrally mounted is employed in which the inlet is effected as indicated by the arrow and the outlet of the chamber is provided by means of the enlarged superimposed tubing 2118 which enters the flange around the tube 207 and sealed at 209. It is connected through a conventional T-fitting 211 with the side outlet 212 serving as a discharge means indicated by the arrow. Thus, fluid pressure is applied to the piston 183 which in turn functions against the head 59 by means of the fluid pressure entering the tubular member 257 at the same time serving as a cooling medium, allowing for discharge therefrom by means of the outlet conduit 212,. Respective connections, as indicated, with the T-fitting, for example, may be made by means of :welds or other suitable forms of conventional pipe connections well known in the art.

A still further modified form of construction with respect to the electrode contact is shown in Figs. 8 and 9. In this structure, the consumable electrode 7 is provided with a contact 213 formed either integral with or else attached to the movable piston 214 in which the outer sleeve 51 and the inner insulating member 215 receives the longitudinally movable piston 214. For a substantial portion of its length, the piston 21 1 is hollow to provide for a chamber 216, the said chamher being closed atone end by means of the threaded cap 217 mounted in sealing relation to the piston 214 by means of the O-ring 218, the said cap being threadedly attached as at 219 to the piston 214. The cap 217 is provided with a central aperture 221 to receive the inlet supply tube 222, the tube being fixedly attached to the cap as by means of the weld 223. At its innermost end, the tube 222 is provided with an annular plate member 224 so positioned relative to the tube and piston as to allow for predetermined axial movement between the innermost transverse end surface portion of the chamber 225 and the said plate member 224 toeifect the desired contact with the electrode 7 by the head 213. Around the liner 51, an annular flange 226 is weld attached preferably as at 227 and is connected in the manner described in connection with the previous figures to another flange member 228 by means of the annularly arranged bolts 229 and having therebetween in fluid sealing relation therewith an insulating flange 231, the bolts being held in place by an insulator collar 232 mounted on the flange 228 under the bolt head as shown. The piston member 214 is provided with an intermediate annular shoulder as at 233 to receive and serve as a base for the coil spring 234, the latter member at its outer end bearing against the transverse surface provided by the ring flange 228 as indicated. I11 order to provide for an absolute seal between the annular flanges 226 and 228 with the insulator ring 231, the O-rings 36 are again employed here and the conduit and passage fluid supply means 37 are again used as described in the other figures. In order to allow for the desired degree of longitudinal movement against the spring 234 by the piston 214, while at the same time providing for a fluid-tight seal between the flange 228 and the outer portion of the piston 214, a bellows 235 is mounted in sealed relation to the flange 228 as at 236 and with the piston portion 214 as at 237. The usual electrical connection with the cap 217 is made at 238 in the manner described previously in connection with the other figures. Thus, it will be clear that a relatively economical as well as a simple means for applying desired pressure to the contact between the consumable electrode 7 and the hen 213 may be made while at the same time permitting the desired circulation of cooling fluids in addition to applying the necessary fluid pressure thereto.

It should thus be apparent that we have provided a novel furnace and consumable electrode feed structure which insures an internal inert atmosphere being maintained at all times. The other main facets of our invention comprising the novel slidably engaging electrode contact and novel electrode feeding means also insure proper electrode contact and an electrode mounting free of objectionable bending or twisting forces.

The depicted structures are obviously subject to many modifications which still fall within the ambit of our inventive principles as determined by the appended claims.

We claim:

1. In an apparatus for energizing a consumable electrode in arc-melting operations, the combination comprising a shell member, an expansible bellows member positioned therein, an electrical lead member positioned therein and traversing the length thereof, a fluid-tight chamber defined in part by said eXpansible bellows member whereby cooling fluid may circulate therethrough, insulating means cooperating with said fluid-tight chamber, a metallic contact shoe member fixedly attached to one outer end limit of said fluid-tight chamber, said cooling fluid entering said fluid tight chamber directed against a transverse surface thereof immediately adjacent the in ner contact area of the said shoe member whereby to spread cooling fluid over said inner contact area under pressure and whereby said expansible bellows member is forced into an extended position in the normal course of operation.

2. In an apparatus for energizing consumable electrodes, a jacketed casing member, a fluid inlet and outlet inserted in said casing member jacket whereby a cooling fluid may circulate therethrough, at least one electrode-contact housing member intersecting said jacketed casing member at substantially right angles thereto, said housing member comprising an expansible bellows member, a fluid-tight chamber defined in part by said expansible bellows member, insulating means around said bellows member within said housing member, said expansible bellows member having one movable end limit, an electrode contact shoe attached to said movable end limit of said expansible bellows member, said fluid tight chamber having a fluid inlet and outlet, said shoe being hollow adjacent the inner end of the contact area of the shoe to receive the fluid inlet in substantially end abutting relation whereby to difluse cooling fluid over the inner end of said chamber and shoe, and a fluid regulating means being aflixed to said fluid outlet.

3. In a consumable electrode enerizing apparatus, the

combination comprising a fluid pressure actuated electrode contact shoe, said contact shoe being affixed to an expansible fluid responsive chamber, said chamber h0using an electrical lead member for energizing said contact shoe, the fluid'for said expansible fluid responsive chamher being in direct contact with said electrical lead member, said expansible' fluid responsive chamber being formed in part by an expansible bellows member, insulating means lining at least a portion of the fluid responsive chamber, said eXpansible bellows member being so formed as to contract in the absence of any internal fluid pressure and being connected to said shoe at a portion thereon relatively removed from the contact area of the shoe and substantially immediately adjacent the inner portion of the lining constituting said insulating means.

4. In an apparatus for effecting electrical contact with a consumable electrode, the combination comprising at least one eXpansible bellows member, said bellows member forming in part a fluid-tight chamber, an electrode contact member afliXed to one end limit of said fluid-tight chamber, an electrical lead member housed inside said fluid-tight chamber and in contact therewith, insulating means comprising an electrically inert liner cooperating with the said lead member, including a suspending radiation shield adjacent thereto, a fluid inlet and a fluid outlet for said fluid tight chamber, fluid diffusing means on an inner end limit of the fluid inlet adjacent an inner portion of the said electrode contact, a valve member connected to said fluid outlet whereby the fluid pressure in said fluid tight chamber may be regulated.

5. In means for effecting electrical contact with a consumable electrode, the combination comprising at least one expansible bellows member, the said bellows member forming in part a fluid-tight chamber and a connection for the electrical power source, insulating means including combined liner and gasket means cooperating with the said fluid-tight chamber, an electrode contact member attached to one end limit of said fluid-tight chamber, fluid inlet and outlet means for said fluid-tight chamber, valve means cooperating with the fluid outlet means whereby the fluid pressure in said fluid-tight chamber may be regulated, the said electrode contact member being hollow to receive an inner end limit of said fluid inlet means, the said latter means being telescopically received for at least a portion of its length within said outlet, one end of said fluid inlet means being arranged in spaced-apart relation to a transverse end surface of said fluid-tight chamber whereby to diffuse cooling fluid through said fluid chamber to the said outlet.

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